Preparation of Benzene Derivatives: The Yu/Baran Synthesis of (+)-Hongoquercin A

Lutz Ackermann of the Georg-August-Universität Göttingen oxidized
(Org. Lett.2013, 15, 3484.
)
the anisole derivative 1 to the phenol 2.
Melanie S. Sanford of the University of Michigan devised
(Org. Lett.2013, 15, 5428.
)
complementary conditions for either para acetoxylation of 3,
illustrated, or meta acetoxylation.
Lukas J. Goossen of the Technische Universität Kaiserlautern developed
(Synthesis2013, 45, 2387.
)
conditions for the cascade alkoxylation/decarboxylation of 5 to give 6.
Cheol-Hong Cheon of Korea University showed
(J. Org. Chem.2013, 78, 12154.
)
that the boronic acid of 7 could act as a blocking group during
electrophilic aromatic substitution, or, as illustrated, as an ortho directing
group. It could then be removed by protodeboronation.

Jun Wu of Zhejiang University coupled
(Synlett2013, 24, 1448.
)
the phenol 9 with the bromo amide 10
to give an ether that on exposure to KOH at elevated temperature
rearranged to the intermediate amide, that was then hydrolyzed to 11.
Dong-Shoo Shin of Changwon National University reported
(Tetrahedron Lett.2013, 54, 5151.
)
a similar protocol (not illustrated)
to prepare unsubstituted anilines.
Guangbin Dong of the University of Texas, Austin used
(J. Am. Chem. Soc.2013, 135, 18350.
)
a variation on the Catellani reaction to convert the
ortho bromide 12 to the meta amine 14.
Kei Manabe of the University of Shizuoka found
(Angew. Chem. Int. Ed.2013, 52, 8611.
)
that the crystalline N-formyl saccharin (16) was a suitable CO donor
for the carbonylation of the bromide 15 to the aldehyde 17.
John F. Hartwig of the University of California, Berkeley described
(J. Org. Chem.2013, 78, 8250.
)
the coupling of the zinc enolate of an ester (Reformatsky reagent), either
preformed or generated in situ, with an aryl bromide 18 to give 19.

Olafs Daugulis of the University of Houston developed
(Org. Lett.2013, 15, 5842.
)
conditions for the directed ortho phenoxylation of
20 to 22. Yao Fu of the
University of Science and Technology of China effected
(J. Am. Chem. Soc.2013, 135, 10630.
)
directed ortho cyanation of
23 to 24. Related results were reported
(Org. Lett.2013, 15, 4960.
)
by Pazhamalai Anbarasan of the Indian Institute of Technology, Madras.
Laura L. Anderson of the University of Illinois, Chicago coupled
(Org. Lett.2013, 15, 3362.
)
26 with 27 to prepare the α-aryl ketone 28.
Kian L. Tan, now at Novartis, optimized
(J. Am. Chem. Soc.2013, 135, 18778.
)
the silyl tether of 29 to direct selective meta alkenylation.

Jin-Quan Yu and Phil S. Baran of Scripps/La Jolla combined forces
(Angew. Chem. Int. Ed.2013, 52, 7317.
)
for the synthesis of (+)-Hongoquercin A (33). Directed regioselective
ortho methylation of 31 followed by directed ortho
acetoxylation led to 32, that was hydrolyzed to give 33.